Kiln for drying lumber and other substances



Dec. 13, 1932. L STEEL KILN FOR DRYING LUMBER AND OTHER SUBSTANCES FiledFeb. 1. 1929 5 Sheets-Sheet 1 bis 5 aws 5 Sheets-Sheet 2 J. STEEL FiledFeb. 1, 1929 H fi rw \w 8*, W ww/ QW mm. $1 um MM. 5V9 mm. M. m

E MI LW KILN FOR DRYING LUMBER AND OTHER SUBSTANCES Dec. 13, 1932.

Dec. 13, 1932. J. l. STEEL 1,890,756

KILN FOR DRYING LUMBER AND OTHER SUBSTANCES Filed Feb. 1, 1929Sheets-Sheet 3 & a l

Dec. 13, 1932. J. I. STEEL 1,890,756v

KILNVFOR DRYING LUMBER AND OTHER SUBSTANCES Filed Feb. 1, 1929 5SheetsSheet 4 Dec. 13,- 1932. J. STEEL KILN FOR DRYING LUMBER AND OTHERSUBSTANCES 5 Sheets-Sheet 5 Filed Feb. 1, 1929 Patented Dec. 13, .1932

Unit-sin? Pa rs-NT" oe,

" JOSEPH" STEEL, on ron'rmrm); oR'EoroN', Assre Non'mdMooRE DRY KICOMPANY/01:" OREGON/ A eonPoRATIoNor'oREGoN Q Kmnk 1103.: nmrmafwivmnnAND OTHER suns'raivo is Mj present invention relates to the productionof improvements in v the' art of kiln. drying andi'n. kilns for drying,lumber and/ 7 other substances.

One important? object of'my invention. is

to effect a. simplification off the duct. system.

for employing cross-circulation of air in kilnsif Another object,

well as to means for, distributing theflmedium' of circulation evenlyanduniformly through tempering thejcirculatory medium, that is to tional''view, partly broken away, ,of'o'ne of" my kilns. taken substantiallyinthe plane of the fan shaftf axis, and showing ifanson the "sa qualifyingthev constituent elements thereof in respect .to their relativeproportions, and in respect to the'temperature, and s humidity of themedium.-

, Other objects achieved by I my invention.

will 'be made apparent to' one skilled in theart by careful perusal ofthe follow ng, spec-Q ification. What constitutes my 'lIlVGDtl'OIifjwill" be d'efinedin the appended claims.

form of embodiment at present preferred,

Figure I is a longitudinal horizontal secshaft and. the fan" conduit ina simple and insofar economical fornrof assemblage;

Figure II is a view similarto that of the theTsame bythe addition ofverticallyfdisopenings of the-"conduit.

Figure III is a view similar to that of the preceding figure; showingbaflie membersof like" form and function ihavin'g supporting 'pla tesextending not only "into the throats is to promote thefgenera'lf'efli'c'iencyof kilns. of the said type; due, in I large; measure, -toemployment. of" special 31 means'for reducing. 'staticainpressure, as

Figure IXl hereinafterdescribed in 'detall andsuccinct- 3o aforesaid butals'd entirely across the interior of theconduit. p

FigureIV' "s a vertical transverse section of one of my single trackkilns of any pre-* 'ferred type" of conduit, showing an. air duct in'g"one of the air intake openings therein.)

superposed above the fan conduit and show-{ Figure V is aviewof-adoubleitrack kiln similar to that" of the-preceding figure,butshowing j-the'air duct below instead of above.

thejcon-duit.v I

Figure VI n i'g ure III, but taken at right angles there Figure virus aview imilar w Figure v of a further modificationuof my device in reis aView similar to that shown-- spect'to the air duct, showing, instead ofone, two ducts on opposite sides of the fan conduit.

Figure VIII is a section on theliriEVIIIl- VIII of Figure 'VI'I.

corner of the kiln at the'side of th-e fioor instead of in themiddlethereof. v

Figure IX is a view corresponding to Fig-. ure-"IV, but showing amodification in re-'- spect to thelocation of the, fan-conduit in one sFigureX is a section on the line Xe-X of F' 'gureXIis a section on ofFigure IX."

1 indicates a kiln structure which mayo-be made of any usual or othersuitable, and apit proved design, and of any materiahshape, i

and dimensions that may be suitable and pre-.- .ferred for the 'purposeintended.

It -is provided within its interior with a fanconduit 2,which may='bemadeof any 1,

suitable and preferred dimensions :and of J any preferred shape incross-section, -andwhichextends within the kiln substantially w precedmgfigure, showingamodification of-.

thefull length of the kiln chamber. It may" be made of any preferredmaterial; such, i for metal.

exampleonly, as concrete, 'woodcrib, or sheet Villustrated,i -to restupon thelbo ttom' 3,.of the f kiln; j and that method of construction ispreferred because it is somewhat more economical than any other; but, ifpreferred, it may be disposed elsewhere within the kiln, and may be, forexample, Without substantial change in shape, disposed below the roof 1i of the kiln structure 1. It is, furthermore,

contemplated'that it may be disposed in any of the four corners of thekiln chamber, as

indicated by the numeral'5 in Figure IX, in whichcase its top or bottom,as thev case may be, and inner side instead of its opposite sides are tobe regarded ashaving openings specifiedbelow. V l.

In the method of construction'of the con;

duit 2 which, for reason aforesaid, is that v preferred, the bottom 8 ofthe'kiln constitutes a the lower wall of the conduit, and prefer ablymade somewhatthicher than theother walls of the conduit as shown forexample in Figure V, to aflord for the conduit a longi tudinally:disposed'foundation plate '6 of augmented stability. Howeverfitpreferred,"

it maybe madeof metaland suspended above the floor of the kilnchamb erspecifiedbelow.

The conduit 2 preferably comprises,in effect, two side walls? and 8extending substantially its full length. Each ofthe wa'lls,

which may be, as above specified, of any suitable contour or relativedlSPSli310n,Y I8Sp6C- tively, is made up, in eifect,of a series ofsecstions, whichare alined longitudinally in series,-but are separatedendwise, each from its neighbor so as to define between, them openings11 and 12.

At its oppositeends, the conduit 2 is pro.-

, vided with similar openings which "are, in

efl'ect, identical with those indicatedfbythe "numerals 11 and 12 exceptthat being.ter-j minal in respect to theconduit, they are dis-; posed,respectively, adj acentto the end walls' of the kiln.

The seriesof openings 11 are those-in the wallt7, and the openings 12are thoseiproe, vided int-he wall 8, when located in'opposi'te sidewalls;. They are, in such case, as already specified, interposed betweenthe sectionsfco'ne stituting the. walls 7 and 8, respectively, and

' may be formed by (:lisposin'gtheopeningded ing sections of one wall instaggered relation ship to those of the otherwall, whatever be therelative disposition ofthe conduit walls in which the openingsareprovided. y

It has beenzindicated that the side walls 7 and 8 are'preferably,forstructural reasons that are deemed to be obvious, of vertical 7disposition to the foundation plate 6. EX-

ceptforsuch structural considerations,.the

openings'12 would fbe proyidedby cutting 6 {out or omitting pcrtionsofthe conduit 2'might otherwise be inthe form of a cylindrical tubeinstead of a tubeof angular cross section; and if so constructed, the

"openings 11 wouldbe, in such case, provided by cutting outor omittingportions of the wall defining conduit 2 on "one side, and the l as withthe side fans are included as a part.

opposite side thereof. The openings 11 and 12 would, of course, be instaggered relationship one to the other, whatever be the form of theconduit, and whatever he the relative disposition of the walls'in whichthey are provided,'as aforesaid.

One of the reasons which control a preferencefor employing a conduit 2of rectangular 1 shape incross-section, is that, by aid of such modeofconstruction, the top plate 130i the conduit 2 may be economicallyincorporated ployed to'divide the interior ofthe kiln structurehorizontallyinto three longitudinal compartments,'one, the dryingchamber 19 disposed above thesaid floor, and the other two, theheatingfan-chambers 20 and 21, that are disposed below it," and areseparately definleld by that continuous conduit wall in which The floor'15 does not extend entirely across the interlor'space of thekilnstructure 1, but defines between its lateral edgesandvtherespectively ad acent side walls 17 and 18,

elongated throats 22that are, in effect, longis .tudinally coextensivewith thelength of the floor. Belowthefioor 15, and in operativepropinquity to the threats 22, respectively, I

provi'deheating means which consist preferably of coils of pipe 23 and24 that are, respectively, in operative communication, in any usual. orpreferred manner, with a suit ablesourceof heat, for example asource, ofsteam supply, not illustrated. l

Thesaid coils may, by diminuation of the spaces between the pipesthereof, be employed toefi'ect a distribution of the circulatory mediumand of the heat whichthey supply to the "interior of the kiln by settingup afstatic pressure within the kiln. When 7 QSO employed, the presenceof pipes properly spaced apart in the; coils 23 and 24, may en suppliedby them and consequently of the cirmay be desirable to effect afreerorless obj plished by. the employment of widely separated pipes inthe coils 23 and 24 in combination with winged battles to aidthe'action, for example, of mutuallyimping'ing currents of airIderivedfrom directly opposing fan deliveries, as are hereinafterspecified.

1 Above the-floor 15 and supported thereon by the cross-beams 16,11:provide one or more tirely obviate the necessity. of any other means forefi'ecting distribution of the heat culating medium. In some cases,however, it 1 structed movementofl the] circulatory m8? dium withinthe'kiln, which may be accomloads, one of 'vvhieh is indieateid by 'iiujm eli 26-. I l isu IV, byway 1 ese i le o rp u aley'qb tre ksi d b e t csi t ng b tWeiPefisxfi. re 1.,sf 8,,e1 ;29, s shotvn' asaecominodatingtvvo series of stock in the kiln around instead of theexample stock loads, the u h the speed; e e' i nesip e 1 any usual or,prefer'r'ed" methofdi of the "pr ieiab 'vjifiawRee s il u rated? aSuc'hhneans may "consistsimply o 1a. mea

Of l Fl' iexamplefiof'a-cgri ingai r v Xemp sa f Side W lls '7 l n oflwWhiehiincon que c of s h; disposition,'extend in opposite" directionssub-'1 stantially from the transverse axle" of each tain orciirtainsextending betiveen the and the stock loads thereunderQQneeur'tain 33 is shovvn in as employedin a single 'trackemliodimeiit of myinv'ention, 1111 Figure V, two curtainsse and 35, for exa,i n{ ple, areshown as roofin an operative proximity tothe outside ripper corners ofthe 'sto'ck' loads, 'respeetive1y Bafiie Walls 38 are providedforfuneltiohing below the stock "loads with like "eifeotasjfthe curtains34 and 35 above the' loadsff H y In Connection with the eurta'ins,ventilate tors and 37, of any usu'alor 'piefer'ratyg are preferablyprovided ihfs eries along tlie'length of the 1 00M, and comi rinnieating" with the throats respectively.

The fan oondiiit 2, is piiovidedl'forjthe ac eomniodation of a sucee'ssion of fans l vhere';

of each next ad acent p eir con prises aright. hand and a left hand fan.For eonveni'enceofi identification; 'eaeh right haii df fanis indi{ fani s indicated by the" iiiiiher al the 41, which; if employed, isrnounted at 'ihte valsiri bearings '42, and ivhielifiexteiidin gThedispo'sitionor the fans in entrees,

r "reverse order on the shaft 41,"ere m 1, not

only counteracts the linef shaifti end in either direetion provided aneven number of fa'n s be employefihutim respegt to their several pointsof location in-"the c0ndi11t'2,

even Without 'jsueh? provision; l the aetiohf jof the fanseffectingsuetioiilend; lof i e el l j ei pe'eite tlireeti h safurtherlii np ortant result 1 of convex infg fallQtheg gs for lya h kample the the b'phiiige ll, on one side of the openings ;12, on theothenside of I the e'ondliit intoiair' outlets. shoiild in this:heohserv'edthat thedireotioniofh;

,0 {the she-1141 is iieversib1eatwi a f "1 S ee eih im yi made H 7 Q2170f unetl'onfasl airint'akes.andthefopenings, the s pportfof asnccessionof sin'gl stoek-i i A 12 as aiil oiltlets 'atIany given instant of time;

. majj he,I' withl udistineti pra ctieal advantage reversedthroughoutthe interior ofthe kiln a, throats'i22 asilliistratediii Figures andVQridors; are relativeterms and denote the eong Wed n;t i e ieieifliadi bet olse t s mditiim f e se -fe 9f u tie ii the e tr es; "$011 h ide=lffihe te (we, dep I w -l t l .j.,ssfi y 1 of ef i v per t ely.mount-aaThe;eei e dnrel n m d ustiee -i moun ing ot the. fans as ispecified inthe last foregoing; sentence is. et ej by :4 Sett ng a a a r ransversel,of ,the-eonduit, so asto constitute? am:

feflective partitiong within theconduiti. The

fan thus eonstitutesin eaehjinstanc'e a parti- .-.';t10n \vl1' 1c h' snone the less efleetivej as such Ibecause it is 5a movable partition,since it serves; to prevent, Wheninrotation, the pas-x ;sage of airinonedireetion, and to eompel'the i A power: and size; establishes inthe plane in {a spectral partition; 7

liregard to the formof embodiment of my inventionillustrated in Figure Iof the drawings. ,jln that'figureeach of the fans ofieach opposing pairof fansjsueksin air on oppom site sidesof each pair and drives the'airdeli'ivk Iery of oneifan against; that o f the ian iwith ,Whiehitfis disposed in] paired relationship.

\ Consequently; the force of delivery frqmoone "whiehjithey meet-jabarrier as effective lasi-a solid vvallwouldhe. ,The plane in' whichthe? ,1 air deliveries meet may, therefore; be desig? ,nated, to employan accepted scientific term,

This consideration should be observed in kitt- Z as ,fan counteraets, toa degree of substantial eX-.

factitlidefthatof the fan opposedito it,;andi" with the effect ofpromoting a constantlateral loutput of airO11 OIIG'SidB'Of thGiCQIldllitZand-Q. W111. rule:- .12 1 A .1 ITE. l llx Lil;

i I Th tth r s tf f; eeim eeee eeee iese currents of air'deliv'e'ry'made by oppositely- 13 tv fa corresponding intake of airon the oppositeside? 4 the housings lt,"filled, substantially as they acting fans ofcorresponding size and power,

is as efiectiye for themaking of output of air on one side of theconduit 2 as ifth-e said ide livery of the two fans were made againstphysical dividing partition wall, exemplle tied in the employmentspecified atthe, oppo site ends of the shaft 4:1 of afsingle instead oftwo" oppositely discharging fpairedf "Fiansi openings llor 12 that areadjacent to the end walls, In such case,ihowever,reyersal of thedirection'of rotationofthe shaitll jwill cause both terminal fans todischarge air delivery against'the end walls, respectively.

- In the method employed for installation'fof the fans, respectively, inaconduitflofrec;

tangulan shape in cross-section, each a fan [is mounted in a fan housing414:, which consti tuteswithin theeonduita transverse partition that isin part a solid one, In such instance are each by the fanenclosedftherein, in combin ation with the sectionscomposingthe walls-7= and 8, for example, constitute what may be termed acontinuousfdeflected or sinuous wall interior oflthe kiln.- Said wall,being closed by walls at top and bottom, defines the coniduit 2. If theconduit 2 bemade, as it maybe, in the form of a cylindrical tube, thehousings 4-4 are unnecessary because the-circular pe riphery of each fanmay fit snugly within the cylindrical conduit without the necessity forhousings which are, in eiiect, frames tojaccom modatethe fansrespectively, to the rectangular shape of condu1t.

stan-tiallyr the same width as the space beitween the stool; load andthe-kilnwalhwhich in some cases may formthe throat,l'1owever defined,its oflice are contribute in operation to the direction offlowofthcatmosphereoftion to drive'suchjflow, in one directionof its ner, againstthe opposite side wall-0f the kiln and with likeieiiect upon the loadedstock. j It maybe observed upon reference to Fig-- ures IX and Mylarexample, that the'desiredl deflection of a single air current resultantfrom "two counteracting currents, is accomplished, with substantiallylike effect, by the {means illlis'trat'ed in either "of those figures.

Asshown in Figure IX, in order to define "the throat 22, the floorl-5,;or its equivalent,

for example the edge of thestock load, should extendpartly across thewidth of the fan con- ,duitgfand furthermore the :iuncture on one "side"wane ofthe fan conduit with the floor "lofafifordsthe means ofdeflecting the single 5' air currentaforesaid through the throat. InFigure IX, also, the" side wan 8 of the fan conduit is shown as exte edin the form of an obliquely disposed deflector 55. i

In FigurefV', however, theside wall 8 above indicated is, with likeefiect, extended direct-y ly to thefloor 15. ,It will, therefore, beevidentthat the angle of disposition of the deflector may be varied atwill within the range of ninety degrees. i

In the, contemplation of invention, the

endiachievediby it through the employment of a d rectedsinglejcurrentproduced by two counteracting currents should not be under-,estiinatedi In that regard,it should be borne in mind} that the volumeof such directed single current s great because of the reduction eresistance of: friction to air flow a ainst the extending. from oneendto the other of the. b

side wallsof the duct with the necessity of y y the augmentation ofpower in order to overcome it, but also a necessary drift in one or theothersdirectionofair longitudinally of the "kiln, ependingupon thevolume of air deliveryifiio'm the fan. a I

d By the employment of a directed single current of circulation derivedfrom counter- With respect to the throat 22,which is subji i a g flthere is secured the "in'entiof aseries of such currentsof expanding andspreading each ofthe currents so as to form, in the combination ofsaidseries y y d e d of such currents, an overlapping circulatory the ialldlt l zp 'l y mven' flow that extends substantially-the full lengthfor the lril-nl Thereby and by elimination of a the drift aforesaid, theresult of a. greater uniformity n11 the drying operation ofcirculathroat against the kiln side wall, it may be observed,upon'reference to Figures IV'and IX for instance, that the angle ofreaction I of said currentproceeding from two opposed fans when directedagainst the kiln side wall will cause reflection of said current beyondthe adjacent corner of the stock load or substantially at the middle ofthe height of the stock load, that is to say, at that point in the loadwhere the effect of the pull of direct fan action from the opposite sideof the load is feeblest. Consequently, one important and distinguishingachievement of my invention is substantially to equalize circulation ofair throughout the kiln, whereby the desideratiun of promotinguniformity of the drying action obtained by circulation is eii'ectuated.

In Figure IX, I show a deflector plate 55, preferably connecting oneside of the fan conduit to the floor 15 of the kiln. The angle at whichthat plate is disposed to the floor,

' or to the side of the load, may be varied at will through a range ofninety degrees; but preferably, the floor 15, or its equivalent, extendspartly across the width of the fan conduit in order to define the throatwhose presence is to afiord discharge of air against the adjacent kilnside wall. This deflection aids I in driving counteracting currents ofair circulation against the adjacent side wall of the kiln when the aircirculation is moving toward this adjacent side wall. The purpose ofthis is to provide, in either direction of circulation, means fordeflecting the currents of air circulation against the adjacent sidewall particularly at the corner of the flat piled stock load adjacent tothe throat through which the entering air passes.

In some cases, I prefer to employ means for directing and distributingthe flow of the circulating medium in such direction as may be desiredthroughout the interior of the kiln.

, For example of said means other than the pipe coils 23 and 24 alreadyreferred to, twowing baflie members may be employed of the substantialV-shape illustrated in Figure II, with the effect of tending todistribute,

with least resistance to their movement, an currents towards oppositeends of the kiln.

Instead of the baliie members 45, those of the modified form indicatedin Figure III by the numerals 46 may be employed with substantially thesame eflect. The baffle members 46 are two-winged like the members 45from which they differ only by the inclusion also of a leg constitutinga Y to a greater or lcssextent even to that of forming atransversecross-partition 47. The cross-partition 47 is always present in effect,even though its actual presence is wanting, it is functionallyrepresented by the 'counteractive discharges of air from the opposingfans that are shown in each one of the several Figures I, II, and III.

The wings of the baffle members 45 and 46, respectively, are, by reasonof having permanency of fiexure, flexibly adjustable at will todifferent correlative angles, with the elfect of dividing the flow ofthe circulatory medium of the kiln and of directing it,'-withindeterminate limitations, as may be desired.

I prefer to provide in operative communication severally with the fansof my kiln, an air duct of any suitable and desired shape, extending thefull length of the kiln. The duct also extends preferably through theend walls of the kiln and is adapted to take in outside air at either orboth ends. Saidduct may be disposed above the fans, as illus-" trated inFigure IV, or below them, as 'illustrated in Figure V, and in either ofthose dispositions is preferably incorporated within the structure ofthe conduit. 2.

Other disposition of the fresh air duct may be made. For example, it maybe built into one or more interior corners of the kiln chamber, asindicated for example bythe numeral 48 in Figure VII. In the lastmentioned instance, communication between the duct and the fans may bemade byuse of a branch intake pipe 51, one or two for each fan.

This fresh air duct may be used in connection with any type of internalfan kiln, such, for example, as a kiln for drying lumber disposed in anymanner of piling, edge piling, flat edge to edge piling, or other types.

The function of the air duct is the same, irrespective of itsdisposition relatively tothe fans, but for purposes of identificationthe duct in Figure VII is indicated by the numeral 48, and that inFigure V is indicated by the numeral 49, and that in Figure IV by thenumeral 50. i

The duct, 48, 49, or 50, whichever be employed, is provided at one orboth ends as preferred with a door 52, by which the admission of outsideair into the duct may be atwill regulated or even excluded if desired.(See Figure VI).

The duct is provided at intervals, determinable by the points oflocation of the several fans, with air intake openings 53 of suitablecapacity and of any preferred shape, one for each fan, whereby air fromthe duct is sucked in by a fan through its opening 53 when the fan is inoperationin either direction of rotation.

Each opening 53is preferably provided with means for regulating itscapacity of air intake, such, for example, as a louvre or adjustablevalve 54, and the width of each is preferably spanned by at least aportion of a housing rim 44 'or other means to prevent air current fromthe fan driving into the interior of the duct instead of being suckedfrom it.

It has been specified above that the conduit 2 may be disposed, forexample, abovefor below the stock loads. In that regard, diagrammaticillustration of the location of the conduit above the stock loads may behad by merely conceiving Figures IV and V or IX, X, and XI, to beinverted or turnedv upside down, and the supports for the stock loadstransposed, accordingly, to the bottom 3.

The provision of an air duct with an air intake in operativecommunication with a fan constitutes an improvement in the art of kilndrying whereby a substantially equal supply of fresh air is mechanicallysupplied directly to each fan by whose rotation it is commingled withthe circulatory medium of the kiln and the atmosphere of the kiln iskept substantially of uniform temper at all times throughout theoperation of the kiln.

In view of the foregoing specification, the following brief descriptionis deemed to be a sufficient explanation of the operation of myinvention.

. In any form of embodiment of my invention, the kiln is charged in theusual manner with a complement of stock loads 26, for example, and theend doors of the kiln, such as are common in dry kilns, are closed.Afterwards, the pipes of the coils 23 and 2a being kept properly heated,the fans are set in motion as by rotation. of the shaft 41.

The stock loads 26, for example, being preferably of the flat piledtype, and the curtain or curtains 3335 being in effect closed, flow ofthe heated circulatory medium of the kiln is maintained transverselythrough the interstices of the stock loads from the plenum corridor tothe suction corridor in either direction of circulation. Substantialuniformity of the drying operation throughout the kiln is therebymaintained. A large vol ume of fresh air may be admitted, and uniformityof the temper of the circulatory medium in cross circulation ismaintained by the aid of the door-controlled air duct communicating withthe fans through the air intake openings 53 thereof respectively.

. In the operation described,the ventilators 36 and 37 are employed asusual in kilns for the purpose of ventilation, those on the air exitside of the stock loads being preferably utilized to the exclusion ofthe ventilators on the opposite side of the loads.

It has been already specified that distribution of the circulatorymedium may be accomplished by a variety of means, of which bafflesconstitute. by way of example, only one instance. The use of baffles isadvantageous but not. indispensable under some conditions, and their usemakes it more practicable to obtain good rec ilts in combination withfans spaced at wide distances apart between centers. That is to say, thediscreet use of baffles may be employed to economic advantage by makingit possible to reduce the complement of fans necessary to kiln of givenSIZE.

Moreover, baffles intermediately disposed between fans so as to deflectthe respective air currents from each of the fans which contribute whatmay be called primary air currents may be employed to set up auxiliarycurrents generated by the meeting of the said primary currents inoverlapping relationship to the conduit sections that are, as has beenspecified, disposed between the openings 11 and 12 in its side walls.

For similar reasons, the use of baffles renders the use of an odd numberof fans in the conduit 2 practicably efficient, in place, if preferred,of an even number of mutually counteractive fans.

What I claim is 1. In a dry kiln, a rotary fan therein, means fordefining suction and discharge sides for said fan, a housing for saidfan, a fresh-air intake adjacent said housing and spaced therefrom,atmospheric communication means between said intake and both ends ofsaid fan housing, whereby upon rotation of said fan in either directionfresh air is inspired at the suction and discharge sides, respect-ively,of said fan.

2. In a dry kiln, the combination of a rotary fan, a duct comprising ahousing for said fan, a fresh air intake adjacent to said housing andspaced therefrom, means of atmospheric communication between said intakeand both ends of said fan housing, whereby upon the rotation of said fanin either direction fresh air is inspired at the suction and dischargesides, respectively of said fan.

3. In a dry kiln, the combination of a series of rotary fans, ductscomprising housings for said fans, respectively, a plurality of freshair intakes adjacent to each of the said housings, respectively, andspaced therefrom, means of atmospheric communication between the saidair intakes and both ends, respectively, of said fan housings wherebyupon the rotation of said fans in either direction fresh air is inspiredthrough a plurality of air intakes to the suction and discharge sides,respectively, of said fans.

4. In a dry kiln, the combination of a rotary fan, a duct comprising ahousing for said fan, a fresh air intake adjacent to said housing andspaced therefrom, said intake having a louver for controlling the amountof fresh air passing therethrough, means of atmospheric communicationbetween said intake and both ends of said fan housing whereby upon therotation of said fan in either direction fresh air is inspired at thesuction and discharge sides, respectively, of said fan.

In testimony whereof, I have hereunto set my hand.

JOSEPH I. STEEL.

